Catheter Evaluation for Endocardial Ablation in Patients With Ventricular Tachycardia

Inclusion Criteria: 1. Documented spontaneous episodes of sustained ventricular tachycardia (must satisfy one) 1. For patients with ICDs: Documented episodes must be four (4) or greater for entry into the study. 2. For patients without ICDs: Documented episodes must be two (2) or greater within two (2) months and the assessment will be performed by a review of ECGs and hospitalization records. 3. Incessant VT due to prior myocardial infarction (defined as present for more than one (1) hour and refractory to or immediately recurrent after administration of antiarrhythmic medication and cardioversion). 2. Spontaneous occurrence of symptomatic ventricular tachycardia despite antiarrhythmic drug therapy or ICD intervention. 3. Left ventricular ejection fraction \> 10% as estimated by echocardiography, contrast ventriculography or radionuclide imaging within the previous ninety (90) days. 4. Age eighteen (18) years or older. 5. Signed Patient Informed consent form. 6. Able and willing to comply with all pre-, post-, and follow-up testing requirements. Exclusion Criteria: 1. Definite protruding left ventricular thrombus on pre-ablation echocardiogram. 2. Myocardial infarction within the preceding two (2) months. Patients with incessant VT (defined as present for more than one (1) hour and refractory to or immediately recurrent after administration of antiarrhythmic medication and cardioversion) may be enrolled if their MI is at least three (3) weeks old. 3. Patients with idiopathic VT. 4. Other disease process likely to limit survival to less than twelve (12) months. 5. Class IV heart failure. 6. Serum creatinine of \> 2.5 mg/dl. 7. Thrombocytopenia (defined as platelet count \<80,000) or coagulopathy. 8. Contraindication to heparin. 9. Women who are pregnant. 10. Cardiac surgery (i.e. ventriculotomy, atriotomy) within the past two (2) months. Patients with incessant VT (present 50% of the time with intervention for a period \>12 h) may be enrolled if their surgery is at least three (3) weeks old. 11. Acute illness or active systemic infection. 12. Unstable angina. 13. Severe aortic stenosis or flail mitral valve. 14. Uncontrolled heart failure. 15. Significant congenital anomaly or medical problem that, in the opinion of the Principal Investigator, would preclude enrollment in the study. 16. Enrolled in an investigational study evaluating another device or drug.